Whatever the U.S. Supreme Court decides in the coming days or weeks on gay marriage, the outcome for same-sex couples in California is unlikely to be as simple or swift as a routine walk down the aisle.

In fact, with a litany of legal scenarios possible, about the only certainty in the U.S. Supreme Court is this: Even a dramatic win for gay marriage rights will not produce June weddings for California's gay and lesbian couples because so many technical legal hurdles will remain.

Gay marriage is on the clock in the Supreme Court, which will decide by the end of this month -- perhaps as soon as Monday -- the fate of California's Proposition 8, the state's 2008 voter-approved ban on same-sex nuptials.

The court will also decide the legality of the 1996 federal ban on same-sex marriage benefits by the end of this term. But for California, the anticipation surrounds the long-simmering battle in the nation's largest state over gay marriage rights.

"It's like sleeping with one eye open," said Kristin Perry, a Berkeley woman who, along with partner Sandy Stier, is at the center of the Supreme Court challenge to Proposition 8.

Even county clerks across the Bay Area are prepared for a summer rush of same-sex couples if the Supreme Court ruling legalizes gay marriage statewide. Theresa Rabe, San Mateo County's deputy clerk-recorder, said her office has extra staffing plans if marriage license requests surge.

Much has to happen to reach that point, however, and any U.S. Supreme Court ruling typically has at least a 25-day aftermath before it becomes final -- which even in the most straightforward outcome would not allow gay marriages to resume in California until sometime in July.

But there are about as many twists and turns in what the Supreme Court could do as there can be in a marriage. Among the possibilities:

The Supreme Court could issue a historic, sweeping ruling striking down Proposition 8, finding any such state ban unconstitutional. This would end the legal debate nationwide, and it could be just a matter of weeks before same-sex marriages could occur in California.

The court could uphold a 2012 federal appeals court ruling that, on narrow grounds, found Proposition 8 unconstitutional. Or the justices could decide they never should have taken up the case, leaving the appeals court decision intact. Either action would clear the path for same-sex marriages in California only.

The court can uphold Proposition 8, ruling that it is a state's right to define its marriage laws. This would surely thrust the issue back into the political arena, where gay marriage supporters would ask the state's voters to overturn the ban.

Finally, the court could muddle the immediate future of gay marriage in California by deciding that Proposition 8 backers never had a legal right, or "standing," to defend the law in lieu of the governor and attorney general, who consider it unconstitutional. This outcome, in short, would send the case back to a federal judge's 2010 ruling finding Proposition 8 unconstitutional.

The latter outcome, which has been considered a strong possibility since the Supreme Court heard arguments in March, has generated the most debate.

The crux of that debate is whether former Chief U.S. District Judge Vaughn Walker's original ruling invalidating Proposition 8 would have statewide effect, or whether it would be confined to the two couples who sued to block the law and their two counties, Alameda and Los Angeles.

Because Walker's injunction covered state officials, Gov. Jerry Brown and Attorney General Kamala Harris are widely expected to argue that clerks across the state can no longer enforce Proposition 8. But Proposition 8 backers, and some legal scholars, say there are serious questions about that interpretation, saying a single federal judge may not have such broad authority.

Andrew Pugno, counsel for ProtectMarriage.com, Proposition 8's sponsors, says there will be further fights, some in the state courts, over the issue if the Supreme Court decides the case on standing grounds.

"There will be a dogfight over what we have to do with Judge Walker's decision," promised John Eastman, a Chapman University law professor who earlier in the case unsuccessfully tried to contest Walker's ruling on behalf of Imperial County.

Lawyers for the couples say Walker's ruling clearly blocks the state from denying marriage licenses to same-sex couples. And many legal scholars agree.

"The ... injunction keeps the governor, the AG (attorney general), the registrar of records, from enforcing Proposition 8," said Erwin Chemerinsky, dean of UC Irvine's law school. "They cannot disobey this injunction, and they would not want to."

In the meantime, everyone waits, starting Monday morning, when the Supreme Court is next scheduled to release rulings. With so much uncertainty, even Perry and Stier have decided to plan "something very intimate" for a wedding because the Supreme Court has made planning a larger ceremony difficult.

"We think about it all the time," Perry said this week. "It's getting so close now. Mondays in June are now all possible days."

Howard Mintz covers legal affairs. Contact him at 408-286-0236. Follow him at Twitter.com/hmintz.